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Challenge: Problem 2

Fig. 1.8 shows Joly's differential steam calorimeter applied to the measurement of the specific heat of a gas at constant volume. The initial temperature of the enclosure with its two large metal spheres is measured. Then steam is passed until the balance no longer needs adjusting in order to compensate for the difference in mass between its two sides that develops once the steam has entered. The final temperature is then measured.

Select items from the Array which indicate how the calculation of the specific heat of the gas is made. Also indicate what influences producing errors in the final result have to be offset - either by experimental design (study the diagram carefully) or by calculation.

In this problem we discuss only the items which should have been included. There may be items which are ambiguous in this respect; but concerning these, you are left to your own judgment.

1
latent heat of steam
2
flow of mass
3
constant temperature distribution
4
mass
5
unwanted condensation of vapour
6
transfer of heat from electrical element
7
temperature gradient
8
radiation losses
9
transfer of heat by vapour
10
temperature rise
11
high thermal conductivity
12
specific heat of substance
13
condensation of saturated vapour
14
rate of temperature drop
15
large surface area
16
insulation against conduction or convection
17
pressure
18
cooling inside the enclosure
19
unwanted conduction of heat
20
thermal expansion